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Postoperative sore throat and hoarseness

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To my beloved family

Life is like riding a bicycle.

To keep your balance you must keep moving.

Albert Einstein

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Örebro Studies in Care Sciences 51

MARIA JAENSSON

Postoperative sore throat and hoarseness

Clinical studies in patients undergoing general anesthesia

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© Maria Jaensson, 2013

Title: Postoperative sore throat and hoarseness. Clinical studies in patients undergoing general anesthesia.

Publisher: Örebro University 2013 www.oru.se/publikationer-avhandlingar

Print: Örebro University, Repro 11/2013 ISSN1652-1153

ISBN978-91-7668-975-2

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Abstract

Maria Jaensson (2013): Postoperative sore throat and hoarseness. Clinical studies in patients undergoing general anesthesia, Örebro Studies in Care Sciences 51.

A common problem following general anesthesia is postoperative sore throat (POST) and postoperative hoarseness (PH). Symptoms directly correlated with less satisfaction according to the patients. The overall aim of this thesis was to describe patients' postoperative sore throat and hoarseness after general anesthesia with endotracheal intubation or laryn- geal mask airway. As well as to investigate the risk factors that are associ- ated with the symptoms, and to test methods that may prevent sore throat and hoarseness after a general anaesthetics. A total of 889 patients are included in the four studies. Incidence of POST varied from 21% up to 52

% depending on endotracheal tube (ETT) size in women (I-IV) and in men was the incidence 32-38% (III-IV). There were no gender difference in POST in study III and IV. The overall incidence of PH varied from 42- 59% (I-IV) in all patients, with no gender differences (III-IV). Following a laryngeal mask airway (LMA) 19% of the patients had POST and 33% of the patients reported PH. Patients with POST do seem to be able to local- ize their pain in the throat (IV). Different risk factors are shown to con- tribute to both POST and PH in men and women (II-III). To intubate with a smaller ETT size, 6.0 vs. 7.0 decreased POST in women in the early postoperative period as well as their discomfort from their POST (I). Only 6% of men who needed a laryngeal mask airway had POST compared to 26% of women. The symptoms are more discomforting after an ETT vs.

an LMA up to 24 hours (IV). More patients have sore throat and hoarse- ness in the early postoperative period, but the symptoms can remain up to almost 5 days postoperatively (I, IV). In summary, sore throat and hoarse- ness following general anesthesia, affects many patients postoperatively.

To intubate women with endotracheal size 6.0 decreases both sore throat and hoarseness postoperatively. Women are more likely than men to have a sore throat when a laryngeal mask airway is used.

Keywords: Sore throat, Hoarseness, Postoperative, Complication, Endotracheal tube, Laryngeal Mask Airway, Gender, Risk factor.

Maria Jaensson, School of Health and Medical Sciences, Örebro University, SE – 701 82 Örebro, Sweden, maria.jaensson@orebroll.se

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LIST OF CONTENTS

LIST OF ABBREVIATIONS ... 9

LIST OF PUBLICATIONS ... 11

INTRODUCTION ... 13

BACKGROUND ... 14

Anesthesia ... 14

Anatomy of the Airway ... 14

The Endotracheal Tube ... 15

The Laryngeal Mask Airway ... 16

Incidence of Sore Throat and Hoarseness... 17

Inflammatory Pain ... 18

Cuff Design and Cuff Pressure in the Endotracheal Tube ... 19

Predisposing Factors... 20

Methods of Assessment of Sore Throat and Hoarseness ... 22

The Difference between Gender and Sex ... 24

Pain and Sex/Gender ... 24

Sex Differences in Anesthesia ... 25

Satisfaction with Anesthesia ... 26

RATIONALE ... 28

AIMS ... 29

Specific aims: ... 29

ETHICAL CONSIDERATIONS ... 30

METHODS ... 31

Settings and Study Population ... 31

Anesthesia ... 34

Outcome Measures ... 35

Postoperative Sore Throat (Studies I-IV) ... 35

Postoperative Hoarseness (Studies I-IV) ... 35

Discomfort (Studies I and IV)... 35

Localization of POST (Study IV) ... 36

Data-Collection ... 38

STATISTICAL ANALYSIS... 39

Study I ... 39

Study II ... 40

Study III ... 40

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Study IV ... 40

Demographic, Background and Medical Variables (Studies I-IV) ... 41

RESULTS ... 42

Incidence of POST in the PACU (Studies I, III and IV) ... 42

Incidence of PH in the PACU (Studies I, III and IV) ... 43

Discomfort from POST and PH (Studies I and IV) ... 44

Description and Localization of POST (Study IV) ... 45

Duration of Symptoms (Studies I and IV) ... 46

Risk factors for POST and PH (Studies II and III) ... 48

Decrease in POST and PH in a Clinical Setting (Studies I, III and IV) ... 52

DISCUSSION ... 53

Postoperative Sore Throat ... 53

Postoperative Hoarseness ... 54

Risk Factors for POST and PH ... 55

Gender Differences ... 57

Methodological Strengths and Limitations ... 59

Clinical Implications and Future Studies ... 63

CONCLUSIONS ... 66

SUMMARY IN SWEDISH ... 67

Delarbete 1 ... 67

Delarbete 2 ... 68

Delarbete 3 ... 68

Delarbete 4 ... 69

ACKNOWLEDGEMENTS ... 70

REFERENCES ... 72

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LIST OF ABBREVIATIONS

CRF Clinical research form ENT Ear, nose, and throat

ETT Endotracheal tube

LMA Laryngeal mask airway

HVLP High-volume low-pressure

ICU Intensive care unit

ID Inner diameter

IL-6 Interleukin 6

LVHP Low-volume high-pressure

MD Medical doctor

NRS Numeric rating scale

OR Operating room

PACU Post-anesthesia care unit

PH Postoperative hoarseness

PONV Postoperative nausea and vomiting POST Postoperative sore throat

RCT Randomized controlled trial RNA Registered anesthesia nurse

RN Registered nurse

VAS Visual analog scale ASA Classification

ASA I Healthy person

ASA II Person with a mild systemic disease e.g. high blood pressure ASA III Severe systemic disease

ASA IV Severe systemic disease that is a constant threat to life ASA V A moribund person who is not expected to live without the

operation

ASA VI A declared brain dead person whose organs are being re- moved for donor purposes

Cormack & Lehane Classification Grade I Full view of glottis Grade II Partial view of glottis

Grade III Only epiglottis seen, none of glottis seen Grade IV Neither glottis nor epiglottis seen Mallampati Classification

Mallampati I Soft palate, uvula, fauces and pillars visible Mallampati II Soft palate, uvula and fauces visible Mallampati III Soft palate and base of uvula visible Mallampati IV Only hard palate visible

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LIST OF PUBLICATIONS

This thesis is based on following papers, and will be referred to in the text with their roman numerals.

I Jaensson, M., Olowsson, L. L., & Nilsson, U. (2010). Endo- tracheal tube size and sore throat following surgery: a ran- domized-controlled study. Acta Anaesthesiologica Scandi- navica, 54(2), 147-153.

II Jaensson, M., Gupta, A., & Nilsson, G. U. (2012). Risk Factors for development of postoperative sore throat and hoarseness after endotracheal intubation in women: A Sec- ondary analysis. AANA Journal, 18(4), 67-73.

III Jaensson, M., Gupta, A., & Nilsson, G. U. (2012). Gender differences in risk factors for airway symptoms following tracheal intubation. . Acta Anaesthesiologica Scandinavica, 56(10), 1306-1313.

IV Jaensson, M., Gupta, A., & Nilsson, U. Sore throat and hoarseness following endotracheal tube or laryngeal mask airway: A prospective study

Submitted

Reprints have been made with the permission of the publishers

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INTRODUCTION

In my clinical work as a Registered Nurse Anesthetist (RNA), one of my most important roles is to ensure that the patients maintain a free airway during surgery. This can be done with different devices, such as an endo- tracheal tube (ETT) or a laryngeal mask airway (LMA). Irrespective of the device used, I have encountered many patients who complain about a sore throat on their way to the post anesthesia care unit (PACU). Additionally, many patients express surprise that their voice is different than it was be- fore surgery. Personnel working in the PACU have also confirmed that this is a clinical problem for patients during the early postoperative period. The RNA is an advocate for the patient, and among other responsibilities, both ethical and moral1, this involves reducing the patient’s pain and discomfort and preventing complications2. This daily clinical problem consequently made me curious about how to better understand this minor but common problem, and reduce its incidence in the future. Can nurses do anything to prevent these symptoms, and are there any risk factors that may predict which patients will suffer from postoperative sore throat (POST) or post- operative hoarseness (PH)? While reviewing the literature, I discovered a variety of ways in which this problem has been tackled. It was also evident that most studies had not examined whether there were any differences between the sexes in how they experienced POST or PH.

Although the literature describes POST and PH as minor adverse events, it is important to avoid them since they are directly related to patients’

‘wellbeing and satisfaction with anesthesia care3.

This thesis is my contribution to knowledge about these risk factors, as well as what actions we can take during anesthesia care that may prevent patients from developing postoperative sore throat and postoperative hoarseness.

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BACKGROUND

Anesthesia

Amongst others, one important aim of good anesthetic care is to achieve a secure airway and to ventilate the lungs in a proper physiological manner.

This can be done in different ways, depending on the patient’s characteris- tics as well as the surgery itself. A safe and secure airway can be achieved by using an endotracheal tube (ETT) or using a laryngeal mask airway (LMA)4. Airway management can be performed by either an anesthesiolo- gist or RNA. However, after prescription by an anesthesiologist, the RNA can plan and administer general anesthesia during elective surgery of American Society of Anesthesiologists (ASA) physical status classification I- II patients2.

Anatomy of the Airway

The pharynx consists of three compartments: the nasopharynx, the oro- pharynx, and the hypopharynx. The hypopharynx starts at the epiglottis and ends at the lower end of the cricoid cartilage. The larynx consists of different cartilage including the cricoid, thyroid, and arytenoid cartilage.

The vocal cords run from the arytenoid cartilage through to the posterior surface of the thyroid cartilage5. The space between the vocal cords, the rima glottidis, is one of the narrowest parts of the airway, the other being at the cricoid cartilage6. Women have a narrower larynx than men7,8. The epiglottis protects the larynx from aspiration or foreign matter. When in- tubating with the Macintosh laryngoscope, the tip of the laryngoscope has to be placed in the vallecula and lifted, which stretches these structures9. The trachea begins just below the cricoid cartilage and extends to the cari- na with a total length of 10-20 cm. in an adult5. Several nerves supply mo- tor and sensory fibers to the airway. The glossopharyngeal and the vagus nerve together innervate the pharynx, larynx, and soft palate. Two branch- es of the vagus nerve, the superior laryngeal nerve and the recurrent laryn- geal nerve, innervate the hypopharynx5.

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ETT placed in the trachea© Maria Bergman

The Endotracheal Tube

The ETT is made of polyvinylchloride (PVC) and has a cuff at the distal end. The cuff is a balloon whose purpose is to protect the lungs against aspiration of gastric contents, and to protect the environment in the oper- ating room from anesthetic gases such as sevorane, desflurane, and nitrous oxide4.

In the 1980s when patients were intubated using an ETT the gold stand- ard was an ETT, with an 8.0 inner diameter (ID) for women and a 9.0 ID for men7. Nowadays, the tubes are normally smaller-size 7.0 for women and 8.0 for men, according to textbooks4,10. However, Stout et al.11 showed that both women and men could benefit from smaller tube sizes, which can reduce their chances of suffering from POST or PH. The risk involved in using an ETT with a smaller ID can be air-trapping (auto-PEEP) and insuf- ficient time to complete exhalation4. However, there seems to be no evi- dence for the latter when using ETT size 6.04. A potential problem, though, is the difficulty of performing a bronchoscopy intraoperatively through a smaller ETT12.

The appropriate ETT size in women and men is still under debate in the anesthesia community. The answer might vary depending on whether the patient is intubated in the short term, as during anesthesia and surgery, or for a longer period of time in the intensive care unit (ICU). A smaller sized ETT can make it difficult to perform bronchoscopy and to ventilate ICU patients12.

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The LMA placed in the hypopharynx © Maria Bergman The Laryngeal Mask Airway

The LMA is a plastic tube with a cuff placed in the hypopharynx. It is in- serted blindly and usually does not require other accessory equipment for insertion. Often it is simply necessary to place the patients head in a sniff- ing position; the mouth opens by itself and thereafter inserts the device.

Sometimes lifting of the lower mandible is required, and/or the index finger of the person who inserts the LMA is used to place it correctly4,13.

The size of the LMA is related to the patient’s weight: Size 3 is used in patients who are between 30 and 50kg, size 4 in patients between 50 and 70kg, and size 5 in patients between 70 and 100kg13. In one randomized controlled trial (RCT) that investigated LMA sizes, 5 vs. 4 in men and 4 vs.

3 in women, the incidence of POST in the PACU was higher in both groups that used the larger LMA. However, using a smaller sized LMA increased the risk of higher intra-cuff pressure14, which can be a risk for increased incidence of POST15, although this did not occur in this study. Another angle was addressed in a study using crossover design, which found that the larger LMA (4 in women and 5 in men) provided a better seal and sig- nificantly more optimal ventilation16. Therefore, it is difficult to generalize since many different variables need to be addressed in the choice of LMA size.

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Incidence of Sore Throat and Hoarseness

The incidence of POST after endotracheal intubation varies between 44 % and 64%of those patients surveyed17,18. Several risk factors can lead to the development of POST after an ETT (Table 1), but the precise reason that the symptom emerges is still unclear. One plausible explanation might be an inflammatory process in the mucosa lining19. The likely cause of the inflammation is thought to be ETT size as well as the cuff design and cuff pressure20. In one study, the authors found that a high cuff pressure, i.e. >

30 cm. H2O, was the cause of tracheal lesions, and these correlated well to the development of a sore throat21. Number of laryngoscopies has not been significantly associated with POST in several earlier studies17,22-24.

The incidence of POST following an LMA is approximately 20%25. It was once thought that POST from the use of an LMA is related partly to the insertion technique, i.e. whether the cuff is inflated or deflated cuff.

However, this does not seem to be related to the development of POST26-28. When comparing a rotational technique (i.e., the cuff is inserted in the mouth and turned counter-clockwise until the hypopharynx was felt) vs. a midline approach (i.e., the cuff is inserted in the patient’s mouth, holding the LMA as if it were a pen, and pressure is applied to the palate pharyn- geal curve until hypopharynx is felt), the latter method seems to decrease the incidence of POST29. Also, high cuff pressure, i.e. >60 cm. H2O, was related to the development of sore throat30,31. A possible confounding vari- able in all studies conducted on this issue is the fact that the LMAs used on the patients came from different manufacturers, i.e. Pro Seal®, Igel®, LMA Supreme®, and LMA Classic®. A systematic review including three different brands of LMAs showed a decrease in POST after an LMA compared to an ETT25. Inconsistent with these results was a study with the secondary aim of investigating differences in adverse upper airway symptoms (POST, PH, and dysphagia) caused by the Proseal® LMA and the ETT. The study found no differences at two hours and 24 hours postoperatively in either symp- tom32.

The incidence of PH is 30-49% after an endotracheal intubation33-37, and 7.5% after laryngeal mask airway25. The etiology of PH is different depending on whether it was caused by the ETT or the LMA. When the patient is intubated, there is a risk of vocal cord injury. In a study by Men- cke et al.37 the authors categorized the vocal cord sequelae by both location (uni-or bilateral) and type. In the authors’ categorization, types of sequelae included thickening of the vocal cords (localized swelling at the vocal pro- cess of the arytenoid cartilage), edema ( swollen mucosa at the vocal cords), erythema (redness of the mucosa with surrounding inflammatory swelling), hematoma (caused by bleeding into the vocal cords), granuloma

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of the vocal cords (granulation tissue remains as chronic, localized, round- ed tissue), and arytenoid dislocation or luxation (displaced arytenoid with limited movement). In this study, the most common type of sequela in the patient was hematoma37. The left vocal cord was more often affected than the right37,38. Prolonged hoarseness can be caused by dislocation of the arytenoid cartilage36,38.

PH associated with the LMA depends on the pressure in the cuff and re- sults in neuropraxia of the laryngeal nerve, which in turn can cause unilat- eral vocal cord palsy20.

Inflammatory Pain

Sore throat described in this thesis is most likely non-infectious19, and re- fers to acute pain due to local tissue injury39 in the laryngeal area after general anesthesia with either an ETT or an LMA. Sore throat is an acute but transient phenomenon.

The pain can be categorized as superficial pain, and is different from deep visceral or deep somatic pain. A noxious stimulus to the mucosal membrane initiates a two-phased pain. Phase I is short- lived and mediated by A- delta fibers, followed by Phase II initiated by C-fibers. The pain con- tinues until the healing process is completed40. The main distinction be- tween acute and chronic pain lies in the duration of pain: Chronic pain refers to pain that lasts longer than three months following the initial pain- ful sensation39.

When a mucous surface with sensory nerve innervation is damaged or injured, a complex series of events begins in the body. The cellular break- down releases biochemical substances that directly stimulate receptors found in the free nerve endings41. The impulse is conducted by different fibers, the fast A-delta myelinated fibers and the slower unmyelinated C- delta fibers. The A-delta fiber gives rise to strong and intense pain, while the C-delta fibers give rise to a diffuse and aching pain42. All tissues are innervated by polymodal A-delta and C-delta receptors; there are also si- lent nociceptors, which are only activated by the inflammatory response.

There are receptors that respond to only one kind of stimuli (e.g., heat) called heat nociceptors. There are also receptors that respond to several types of stimuli and they are called polymodal receptors. Tissue damage is always accompanied by an inflammatory process41. Nociceptive pain is described as pain due to tissue damage and can be caused by mechanical stimulation of nociceptors. Different areas of the body have different densi- ties of nociceptors. There are fewer pain receptors in the internal organs,

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which makes it difficult for a patient to localize precisely pain emanating from the internal organs42.

No study has yet pinpointed the precise location of postoperative sore throat and its precise etiology is still unclear. One hypothesis from a swine model is that POST is an inflammatory process involving the cytokine in- terleukin 6 (IL-6)19. This inflammatory process was confirmed in a small study in 14 patients undergoing short term intubation for a median dura- tion of three hours. In this study, the levels of three cytokines, including IL- 6, were measured from the tracheal lavage and were found to increase over time. The authors concluded that the human trachea might respond to a foreign subject, i.e. the ETT, by releasing inflammatory markers43.

Pain perception is always personal and subjective. Pain is defined by the International Association for the Study of Pain (IASP) as

“ an unpleasant sensory and emotional experience associated with actual or potential tissue damage”39.

Cuff Design and Cuff Pressure in the Endotracheal Tube

There are two different types of cuffs, the low-volume high-pressure (LVHP) cuff and the high-volume low-pressure (HVLP) cuff. Both cuffs have advantages and disadvantages. The LVHP cuff has a small diameter and requires high intra-cuff pressure to overcome the low compliance in the cuff. There are two disadvantages of this high pressure: the risk of is- chemia in the tracheal mucosa, and risk that the cuff might inflate in a noncircular fashion and injure the trachea44. The HVLP is larger and corre- lates closely to the pressure in the trachea44. Nonetheless, the LVHP cuff is associated with a lower incidence of POST than the HVLP cuff45-47. The reason for this could be that the HVLP cuff has a larger diameter and a longer cuff length, and thus comes into more contact with the tracheal mucosa48,49.

High cuff pressure exerts high pressure on the tracheal mucosa. The ide- al cuff pressure has been suggested to be between 20-30 cm. H2O50. A cuff pressure greater than 34 cm. H2O decreases the perfusion in the tracheal mucosa50, and a total obstruction of blood flow occurs >50 cm. H2O51. One risk of a low cuff pressure (i.e., seal pressure) is micro aspiration, es- pecially with HVLP cuffs in patients admitted to the intensive care unit (ICU)52. This could be because excessive material in the cuff allows micro- particles to pass through into the trachea, unlike when the red rubber LVHP cuff was used. Through these channels, fluid may pass to the lungs and result in micro-aspiration53. The shape of the cuffs may also increase the risk of micro-aspiration54.

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Different techniques to fill the cuff have been described in the literature.

What is known as the “predetermined technique” for inflating a cuff in- volves injecting a predetermined amount of air. An increase from 0.5 to 9.0 mL. of air can increase the cuff pressure from 2 to 120 cm. H2O55. It has been shown that there is an inter-individual variability in the volume of air needed in the cuff (2-4 mL. of air may be adequate for most patients to achieve a pressure between 20-30 cm. H2O), and an adequate seal56.

The “minimal leak technique” involves the injection of a small amount of air into the cuff and thereafter the aspiration of a small amount of air until a minor leakage is noted at peak inspiration55,56.

The “minimal occlusive volume technique” is almost the same as the

“minimal leak technique”, the difference being that after inflation, a small amount of air is removed until a leakage is heard. The lowest possible vol- ume of air is then injected again to attain a seal at peak inspiration. This technique is perceived to be better at preventing aspiration57,58.

The final technique, and also the most unreliable, is palpation of the pi- lot balloon to assess the cuff pressure. This technique increases the risk of high cuff pressures50,59,60.

Cuff pressure can change during surgery. One study reported that 86%

patients had changes in cuff pressure when they were moved from the su- pine to the prone position in spine surgery with their head rotated to the right61. Without continuously measuring cuff pressure, it is impossible to secure the airway and ensure that the patient is not harmed52,58.

Predisposing Factors

Previous studies have highlighted different risk factors for POST and PH after an ETT. Some of these risk factors have been confirmed by multiple studies, while others have not. It is important to bear in mind when read- ing the studies that different brands and sizes of endotracheal tubes were often used. The patient scenarios are also different, and often the analysis is performed for men and women combined, which may add a gender bias.

This makes it somewhat difficult to evaluate the external validity of the studies (Table 1 and Table 2).

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Table 1 Risk factors for POST in intubated patients described in earlier research

Risk factors for POST Reference

Age (yrs.):

30-39 Chen62

31-40 Hisham23

≤70 Honma63

Blood on the ETT Biro64

High cuff pressure Combes21 ,Ratnaraj65 Duration of surgery (minutes):

>90 Kloub17

>120 Chen62

ETT size Hisham23, Stout11

Female sex Biro64, Chen62, Christensen24 ,Higgins22, Maruyama66, Myles67 ,Ratnaraj65

Smoking habits Biro64

Type of surgery:

ENT Surgery Chen62, Christensen24, Hisham23 ,

Gynecology Higgins22

Use of lidocaine spray Maruyama66, Hara68 Use of naso-gastric tube Honma63, Kloub17 , Use of oral airway Kyokong69

POST=Postoperative Sore Throat ENT= Ear-Nose and Throat surgery ETT=Endotracheal tube

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Table 2 Risk factors for PH in intubated patients described in earlier re- search

Risk factors for PH Reference

Duration Yamanaka36

ETT size Stout11, Al-Qahtani70

ETT vs. LMA Abdi71

Female sex Maruyama66

No use of muscle relaxant Mencke37, Mencke72 PH=Postoperative Hoarseness

ETT=Endotracheal tube size LMA=Laryngeal Mask Airway

Methods of Assessment of Sore Throat and Hoarseness

The research on POST dates back to the late 1970’s73,74. Different scales have been used to measure POST. Often it is poorly defined and described by the patient simply as a sore throat19. The preferred scales to measure POST are a numeric rating scale (NRS), a visual analog scale (VAS), di- chotomous answers or a four grade scale (with the numbers 0-3 corre- sponding to no, mild, moderate, and severe pain), presented here in a ran- dom order (Table 3)Since there is considerable variation in published stud- ies on the incidence of POST due to the size of ETT used, the time-point for its measurement as well as the scales used to measure it, no consensus exists for the measurement of POST. When measuring PH, a binary scale is often used (yes/no) rather than more invasive but more precise methods such as a stroboscope36,37 or a voice recording35,75. There is, however, a four-grade scale that has been used in a study by Mencke et al.37.

When should POST and PH be measured? Although there is no clearly defined time to do so, POST seems to be worst for the patient in the early postoperative period, and therefore it is important to measure it in the PACU76. It is also important to ask direct questions in order to elicit clear responses from patients about POST77. In contrast, PH can be a prolonged symptom that affects patients for varying amounts of time34,36,38. Xu et al.

found that patients suffered from PH after an endotracheal intubation for lengths of time ranging from one day to 45 days, while one patient had PH for 155 days postoperatively38.

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Table 3 The influence of ETT size, gender and time of measurement on POST and PH

Scale Outcome variable

ETT size

Sex Time of

measurement

Reference

VAS POST 7.5 Ƃ

8.0 ƃ

Ƃ+ ƃ Between 12-24 h from extubation

Biro64

Yes/No POST/PH 7.5 Ƃ 7.5 ƃ

Ƃ+ ƃ 1h, 24h and after 1 week

Ratnaraj65

Yes/No PH 6.0-6.5

Ƃ 7.0-7.5 ƃ

Ƃ+ ƃ Within 24 h Al-Qahtani70

Yes/No POST 7.5 Ƃ

8.5 ƃ

Ƃ+ƃ Between 6-24h from extubation

Kloub17

Yes/No POST ? Ƃ+ƃ 24 h Higgins22

Yes/No NRS

POST/PH 7.0 Ƃ In the PACU Abdi71

NRS POST/PH 7.5 Ƃ 8.0 ƃ

Ƃ+ƃ 2h and 24h Combes21

0-3 POST 6.5 Ƃ 7.0 ƃ

Ƃ+ ƃ In the PACU Chen62

0-3 POST 7.0-9.0 Ƃ+ ƃ ? Hisham23

0-3 POST/PH 7.5 Ƃ

8.5 ƃ

Ƃ +ƃ In the PACU and 24h

Kyokong69

0-3 PH 7.5 Ƃ

8.5 ƃ

Ƃ+ ƃ 24 and 72h Mencke37

0-3 POST/PH 7.0-8.0

Ƃ 8.0-9.0 ƃ

Ƃ+ƃ In the OR and 24 h

Maruyama78

0-3 POST/PH 6.5 or

8.5 Ƃ 7.0 or 9.0 ƃ

Ƃ and ƃ 24-48h after anesthesia

Stout11

VAS=Visual analog scale. NRS=Numeric rating scale. POST=Postoperative Sore Throat.

PH= Postoperative Hoarseness. PACU= Post Anesthesia Care Unit. OR=Operating room.

h=Hours. Ƃ+ƃ= Analyzed as a single group. Ƃ and ƃ=Analyzed separately. ?=Not described

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The Difference between Gender and Sex

Sex refers to the biological differencesand chromosomal between men and a women79. However, gender is more than the biological individual; it de- scribes the femininity or the masculinity of a person80. Gender involves the interaction of men and women and involves power and hierarchy79. One concept is “doing gender” which can be described as a process which re- shapes in the actions that we perform as human beings79,81. It can be a dif- ficult to contravene the norms of what society believes to be feminine or masculine behaviour79,81.

Health care today often treats the male sex as a default; in short, what men do or say is the norm79,82. Therefore, masculinity is seen as superior to femininity79. Western medicine is strongly influenced by positivism and a search for the cause of a disease without necessarily incorporating culture, social factors, or subjectivity into research79.

Research that investigates differences between men and women describes biological differences between the sexes largely without taking into account gender79. Having said this, it is also important to acknowledge current research in medicine, which often takes gender into consideration, for ex- ample, differences between reported symptoms or behavior in men and women in contact with health care79,81.

Pain and Sex/Gender

Responses to pain stimuli are thought to be taught during early child- hood80. Many studies have investigated sex differences in the responses to experimental stimuli, without any conclusive results. However, experi- mental studies have shown a difference between men and women in pain threshold and tolerance to pain80. Whether these results are due to different expectations in gender-specific behaviour or differences in sex is still being debated.

There are several experimental studies in the literature concerning gen- der-specific expectations towards pain. One study investigated expectations of pain in men and women and demonstrated that both men and women expected the typical man to report less pain for common pain events83. At the same time, results were presented from another study in which the observers of a short video clip rated men to have less pain than women. In other words, the female observers rated significantly higher pain intensity than the male observers and the women rated observed pain scores higher than the men84.

However, in another study, another approach was used. Here 120 stu- dents were divided into three groups with equal numbers of men and

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women in each group. Every group would rate their pain intensity when holding their hand for as long as they could in cold water. The study de- sign involved presenting gender specific expectations to two of the groups i.e. the instructions were that “the typical man/woman last 30 seconds on this task” or the typical man/woman last 90 seconds on this task”. Finally, one group was given the instruction to last for as long as they could. In the latter, men had longer tolerance time, and women reported the water tank as more painful. However, when given gender-specific tolerance expecta- tions there were no differences between the sexes85. The results from these studies must be interpreted with caution, since the participants in these experimental studies are often young healthy students and therefore the results cannot be generalized to all patients within the health care system.

These studies are in contrast to the results from an experimental study in a clinical setting including 14,988 adult patients receiving patient con- trolled epidural analgesia (PCEA) after major surgery. The result showed there were almost equal pain scores at rest and on movement between men and women although women had lower total PCEA consumption consist- ently during the 5 days follow up86.

Sex Differences in Anesthesia Greenspan et al. state,

“We recommend that all pain researchers consider testing their hypothesis in both sexes, or if restricted by practical considerations, only in females”80. This is to reduce the risk of generalizing results that have been investigated only in males. More and more research points out that there are differences between men and women in the emergence from anesthesia87,88, the quality of postoperative recovery87, and pain response88, as well as pharmadynamic and pharmacokinetic response89. It seems that women have a different recovery profile than men88. Even though women emerge faster from gen- eral anesthesia88,90, their Quality of Recovery (QoR) is poorer than that of men. Women rated higher pain scores in the PACU and in the first three days after surgery. Women also experienced more postoperative nausea and vomiting (PONV) and longer stay in the PACU than men88. One ex- planation for the observed gender differences might be physical differences between the sexes. Men and women have differences in body mass index, percentage of body fat, and differences in total body water, and hormones89.

Myles et al. suggest that there is a sex difference in the ability to report postoperative symptoms, and that women may find it easier to report symptoms to a nurse than men do67. It is also possible that patients report

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symptoms differently to different healthcare workers. In one study, female patients consistently gave lower VAS pain scores to the RN than the sur- geon91.

Satisfaction with Anesthesia

Satisfaction with anesthesia has been defined as,

“The balance between what is expected and the perception of what is re- ceived”92.

In a Delphi study, a panel of anesthesiologists’ investigated 33 common outcomes that may be important to avoid, from a patient perspective. The panel agreed that POST is a common postoperative outcome. However, when reporting how important POST would be from a patient perspective, the anesthesiologists placed POST just 25th out of the 33 outcomes93. When the patient perspective was investigated, the picture was somewhat different. Although POST was not the most important side effect to avoid even from a patient perspective, POST can decrease the experience of anes- thesia itself18,94-96.

In order to improve patient satisfaction after anesthesia, studies have shown that it is important to provide proper preoperative information97,98, and a postoperative visit by the anesthesiologist or registered nurse anaes- thetist (RNA)92,99. It remains unclear how many postoperative visits are best for the patients, one99 or more than two92. Saal et al. reported that patients were dissatisfied with “continuity of anesthesia care” if they were not told who would conduct the postoperative visit. If the patient expected an anesthesiologist, they were dissatisfied if an RNA visited99. The majority of a cohort of ambulatory patients from Scotland was significantly more satisfied if they had someone to contact if a problem arose after dis- charge98. Also, patients are more likely to be highly satisfied when they are provided with clear and accurate information about the phases of anesthe- sia92. At 30 days after surgery, strong predictors of satisfied patients were clinical information, low postoperative pain scores in the PACU, and the final surgical outcome97.

What information the patient wants seems to differ between patient and professionals. One study from the Netherlands identified important areas of information observed from two perspectives, the surgeon’s and the pa- tient’s. The results revealed that information about anesthesia e.g., type of anesthesia, variations in anesthesia, complications of anesthesia, sensations during anesthesia, and relief of tension, as well as information about the

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early postoperative recovery were all highly significant from the patient’s perspective but not from the surgeon’s perspective100.

The importance of decreasing minor adverse events was shown in a large study with over 10,000 patients. They were all interviewed within 24 hours after anesthesia for a number of events (i.e., POST, PONV, back pain, urinary retention, confusion, neurological deficit, myocardial infarct, hepa- titis, renal failure and pain) and were asked to rate if they were satisfied or dissatisfied with the anesthesia care. The incidence of dissatisfied patients was 0.9%, while 2.3% were “somewhat dissatisfied”. When adjusted for patient and surgical factors, the results showed that any postoperative complications described earlier (pain and PONV excluded from analysis and analyzed separately) increased the risk of being dissatisfied (odds ratio (OR) 2.04, 95% CI 1.64-2.56, p<0.001). Additionally the risk of patient dissatisfaction increased along with postoperative complications96. This is supported by another large survey from Switzerland with over 12,000 pa- tients who were interviewed between the second and fifth postoperative days. Patients rated POST and PH second and third, respectively, on the list of complications they found concerning. Their satisfaction level was generally high, but dissatisfaction was clearly associated with at least one adverse event3. Also, women were at greater risk than men of dissatisfac- tion with pain management regimes101. Therefore, it is important to inves- tigate anesthesia quality with objective and valid instruments102.

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RATIONALE

Postoperative symptoms of sore throat and hoarseness after intubation can be annoying for patients. The exact cause of these symptoms is not fully understood. Selecting the size of the endotracheal tube in adults is often standardized4 and rarely customized. Previous studies have shown that women are more susceptible to sore throat after intubation, and the endo- tracheal tube size may be the cause of these symptoms. Only one study has previously examined the difference between the sizes of endotracheal tubes in a female population. It is therefore important to examine differences in the onset of symptoms in women if they were intubated with different sizes of endotracheal tube.

No observational study has previously examined a population of women intubated with endotracheal tube size 6.0. Therefore, examining a popula- tion of men and women in order to systematically understand and investi- gate intraoperative airway management and patient characteristics that lead to postoperative symptoms fills an important gap in our knowledge.

Furthermore, establishing the differences between men and women in air- way related symptoms is important so that endotracheal intubation can be performed safely and correctly.

Another factor that contributes to postoperative symptoms is the use of LMA, even though the incidence of POST is lower when using an LMA compared to an ETT. To my knowledge, there have been no studies that have evaluated the difference in pain localization, between ETT and LMA and none that have investigated differences between men and women on how they respond to ETT compared to LMA.

Postoperative hoarseness following general anesthesia has also not been investigated thoroughly34.

By filling these gaps in our knowledge, we may be able to reduce the risk of unnecessary suffering from POST and/or PH for patients undergoing general anesthesia.

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AIMS

The overall aim of this thesis is to describe patients' postoperative sore throat and hoarseness after general anesthesia with endotracheal intuba- tion or laryngeal mask airway. The thesis also aims to investigate the risk factors associated with post-operative sore throat and hoarseness, and to test methods that may prevent sore throat and hoarseness after a general anesthesia.

Specific aims:

I To compare whether women intubated with ETT size number 6.0 had less sore throat compared with women intubated with ETT size number 7.0. The secondary aims were to investigate the risk of hoarseness and discomfort from sore throat and hoarseness, as well as duration of these symptoms.

II To identify risk factors associated with POST and PH in women follow- ing endotracheal intubation. The aim was to add to our knowledge about predictors of sore throat and hoarseness in patients undergoing surgery with an ETT, in order to maintain a free airway.

III To describe independent factors that may be associated with the devel- opment of POST and PH after endotracheal intubation in adults, as well as whether there are any gender differences.

IV To determine the differences in the incidence of postoperative sore throat and hoarseness following laryngeal mask airway or endotracheal tube, and whether there are any specific gender differences in these adverse events, as well as to determine the location of sore throat and the duration of these symptoms.

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ETHICAL CONSIDERATIONS

The Declaration of Helsinki103 and good clinical practice were followed in all four studies. Ethical approval was obtained from the Regional Ethics Committee, Uppsala, with the following reference numbers: 2008/023 (I, II), 2011/086(III) and 2012/392(IV).

Informed consent was obtained as follows: When eligible patients were referred to surgery, the department nurse sent an information sheet home to the patient. A form for informed consent was also included in the enve- lope. On the day of the surgery, before any premedication was adminis- tered, the researcher visited the patients and written consent was obtained.

The aim and intentions of the study were carefully explained, as well as, the scales used and the reasons why patients’ reported outcomes were col- lected several times postoperatively (I).

In study III, the Regional Ethics Committee exempted written consent since no intervention was planned and only standard anesthesia care was used. Only verbal consent was obtained prior to anesthesia. The RNA asked the patient before induction if the patient consented to be questioned about POST or PH in the PACU. However, even non-written consent must be carefully documented and therefore the patient’s participation in the study was documented on the clinical research form (CRF) and in the anes- thesia record. All patients were given written information about the aim of the study and the outcome measurement.

In study IV, eligible patients were recruited during the preoperative check-up visit or on visits to the Ambulatory Unit on the day of the surgery by the researcher or a trained research nurse. Written consent was collected before surgery. Consent to participation in the study was documented in the patient’s electronic data record and in the CRF.

In studies I, III and IV all patients were informed that they could with- draw at any time without affecting further anesthesia care. In order to protect patients’ privacy, the data collected were coded a manner such that no individual could be recognized.

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METHODS

The studies included in this thesis are primarily quantitative in nature, including one study that has experimental design and three studies that are prospective but without experimental designs. Table 4 presents an over- view of all four studies, which will be referred to as studies I-IV throughout the text.

Table 4 Study design of studies included in this thesis.

Study I II III IV

Design RCT A prospective

cross sectional study ; a secondary analysis

A prospective observational study with a cross sectional design.

A prospective longitudinally study with a descriptive design Participants

Sex

n=100 Women

n=97 Women

n=495 Men and women

n=301 Men and women Outcome

variables

POST: Four graded scale PH: Binary scale Discomfort:

Four graded scale

POST: Binary scale PH: Binary scale

POST: Four grad- ed scale PH: Four graded scale

POST: Four graded scale PH: Four graded scale

Discomfort: Four graded scale Location: Five different meas- urements and a photograph RCT=Randomized Controlled Trial. POST=Postoperative Sore Throat.

PH=Postoperative Hoarseness. PACU=Post Anesthesia Care Unit.

Settings and Study Population

All studies were conducted in the Anesthesia Department at the University Hospital in Orebro. However, the patients were recruited from different surgical departments.

In studies I and II, the patients were anesthetized for the Plastic Surgery and Ear, Nose, and Throat (ENT) departments. Study III included patients from several surgical departments, including the Eye, Plastic, ENT, General Surgery, Orthopedics, Hand, Urology, and Gynecology departments. Final- ly, in study IV, the patients were recruited from the General Surgery-, Or- thopedics-, Hand-, Urology, and Gynecology departments.

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The patients were recruited between March 2008 and December 2008 (I- II), May, and September and November 2011 (III), and January and April 2013 (IV).

The inclusion criteria were as follows: women ≥18 years (I-II), men and women ≥18 years (III-IV) , anesthesia for more than 90 minutes’ duration (I-II), elective surgery (I-IV), supine position (I-II), ASA I-II (I-II), oral intu- bation (I-IV) with one or two attempts at laryngoscopy (I-II), need for an laryngeal mask airway (IV), and clear understanding of the Swedish lan- guage(I-IV) and possessing of a telephone for a follow-up call (I).

Exclusion criteria were as follows: anesthesia with rapid sequence induc- tion(I-II), the use of succinylcholine (I-II), surgery in the throat and mouth area (I-IV), an on-going throat infection (I-II, IV), acute surgery (III-IV), nasal intubation (I-IV), esophageal probe inserted, and expected duration of surgery >240 minutes (IV).

Of the 896 patients included in this thesis, 578 were women and 318 were men. Study I included 100 women. However, three was excluded (Figure 1), therefore 97 women are included in the analysis (I, II). In study III, 292 women and 203 men were enrolled. In study IV, 186 women and 115 men were enrolled. In one patient, several attempts were made to in- sert a Proseal LMA, but it was unsuccessful and he was subsequently intu- bated. Two men and one woman had to be intubated during surgery, be- cause of in adequate ventilation using an LMA. These four patients were excluded from the analysis. Therefore, from a total of 889 patients en- rolled, 574 were women and 315 were men.

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Figure 1 Flow Chart of the participants in study I and II RSI=Rapid Sequence Induction. ETT=Endotracheal intubation.

PACU=Post Anesthesia Care Unit.

Figure 1. : Study flow chart of the trial.

Abbreviation: RSI= Rapid sequence induction

Allocated to intervention ETT 7.0 (n= 50 ) Allocated to intervention

ETT 6.0 (n= 50)

Assessed for eligibility (n= 118)

Excluded (n= 18) Refused to participate (n= 6) Did not meet inclusion criteria (n=5) Other reasons (n= 7)

Time Follow-up Analyzed PACU n= 48 n= 48 24 hours n= 48 n= 48 72 hours n= 18 n= 18 96 hours n= 8 n= 8

Time Follow-up Analyzed PACU n= 49 n= 49 24 hours n= 49 n= 49 72 hours n= 23 n= 23 96 hours n= 8 n= 8 Randomized

(n=100)

Excluded;

RSI (n= 1)

Received allocated intervention (n= 49)

Received allocated intervention (n= 48)

Excluded;

RSI (n=1) cold (n=1)

Excluded from analysis at 72 and 96 hours non responding follow up call (n=1)

References

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